Oil vs Grease vs Dry lube

Most modern firearms are designed for use with oil. Certain older firearms (such as the M1 Garand) are designed for mil-spec grease, not oil. It is worth noting that grease tends to attract and embed soot, dirt, and other contaminants to a greater degree than oil will. "Dry lube" is typically a graphite powder, which is significantly better than oil at not attracting contaminants in desert conditions. Arabian desert sand is a very fine powder (finer than that in American deserts), and a conventionally oiled low-tolerance rifle will rapidly pick up so much sand in its action that it will malfunction in short order. High-tolerance rifles such as the AK-47 are less inclined to malfunction from the combination of oil and sand, but their reliability does improve as well with the use of dry lube in desert conditions. Interestingly enough, the US Army has found that heavy lubrication improves reliability on the M-4/M-16 platform in sand, vs light lubrication.

Basic Components commonly found in Lubricants and Cleaners

This section comes before the writeups on the various compounds, because many of the products share the same base chemistry. So rather than write up what each lubricant will do, it's useful to define what the families of compounds will do and then simply note that the active ingredient in product X, is chemical family Y.

Graphite: It's a bit more common to see moly (see below) than graphite, but some dry-lube does use graphite. Because graphite and molybdenum disulfide behave the same way (except for the fact that graphite breaks down at a lower temperature than molybdenum disulfide), see the moly point for details here.

Halogenated Hydrocarbons: One fairly common example of a halogenated hydrocarbon, is chlorinated parrafin - basically chlorinated wax. The problem with all halogenated hydrocarbons is that as they decay, they precipitate acid, which will readily attack the metal which they're on. The decay tends to occur either over time, or when subjected to physical stress or temperature. It's worth noting that HH's activate at a temperature which tempts gun owners to 'bake' their guns in order to fully activate them. However, according to posts by 'Firepower' (Purportedly of MPC corporation), metal-on-metal friction of slides and other components moving against each other create a momentary temperature of 210 degrees at minimum, which is within the activation threshold of the chemicals in question. A good example of temperature obtained through friction, is found by simply rubbing your hands together.

MPC claims that they use epoxidized oils in their FP-10 CLP product to capture these acids upon precipitation, before they get the chance to attack the underlying metal.

Molybdenum disulfide: A key ingredient in 'moly grease', molybdenum disulfide is fairly non-reactive with various metals. It's also used in some oils. It's important to note that moly does not protect against corrosion. However, solutions employing moly as a lubricant may employ other anti-corrosive compounds.

Siloxanes: Siloxanes a family of chemicals which claim to stick to ferrous (i.e. iron bearing, such as iron or steel) metals and create a thin film of lubricant. Like any dry film, they will not flow back into areas where the film has been rubbed off, unlike oil. They are related to silicone, but not the same.

Teflon: Teflon is a form of Polytetrafluoroethylene, which is also used as a "non-stick coating" for cookwares.

Precipitation: When suspended in any lubricant, over time it will settle out. This isn't a big problem; just shake or stir it to re-mix it, then spray or otherwise apply it to your weapon.

Evaporation: Starting at 260 degrees, teflon begins to emit fumes which can kill birds. It is generally marketed as 'safe for humans' provided that the temperatures do not exceed 500 degrees. However, at 680 degrees, large volumes of toxic fumes are emitted. Polytetrafluoroethylene poisoning exhibits itself as "flu-like symptoms"... a fever, headache, chills, backache, etc. It is also worth noting that heated teflon will 'clump' at a certain temperature.

Synthetic esters: This is frequently encountered in synthetic oils (the other common type of oil is polyalphaolefin). It's also worth noting that ester oils are water-soluble and, worse, will actually break down to form water over time.

Cleaning and Lubrication Products

In my dream world, I'd be able to readily obtain information for each item, regarding:

Corrosion risk

Clinginess to metal

Dermal Irritation

Evaporation / Vapor toxicity

Flammability

Risks to wood, polymer, rubber, and electronic components (yes, folks with laser sights deserve to know what will eat their PCB's!)

Ed's Red Bore Cleaner

"Ed's Red" is Ed Harris's homemade formulation for cleaning bores and parts. It is not a copper solvent, so you'll need to run a dedicated copper solvent (such as Hoppes) for that role. However, it does a fine job of dissolving lead and powder residue. It's worth knowing that this bore cleaner will attack wooden surfaces if left on; it is not documented how it will react to rubber or synthetic materials. You can find the recipe here.

Mobil 1

This is primarily an automotive oil, but some folks do use it on their firearms. It's worth noting that it's a polyalphaolefin compound (PAO).

Hoppes / Castrol Oil

It seems that Hoppes has Castrol make their gun oil. Their oil is composed of a synthetic ester. Users have reported that Hoppes oil will 'run off' of the slide rails after a couple of weeks of storage.

Sentry Solutions Smoothkote

It is worth noting that Smoothkote has difficulty in binding to any surface which has previously been treated with teflon. Its lubricity is achieved through use of molybdenum disulfide. Regardless of composition, user reports state that you must be meticulous with degreasing and metal preparation, in order to make effective use of Smoothkote. It also requires multiple applications, but when complete it's a pretty durable coating.

Eezox

Eezox is a synthetic, non-petroleum-based metal treatment. It's theorized that it's silicone based. The advantage is that it provides superb resistance to corrosion; the disadvantage is that it's more inclined to rub off than other solvents. Silicone also

TW-25B (by Mil-Comm)

As a synthetic oil, TW-25B will separate and should be shaken or stirred before use. This isn't that big a deal; you have to shake/stir CLP too. TW-25B is also a pure lubricant, without powder solvent capability. It's been recommended as a magazine lubricant, as it's a dry lube and won't attract grime. It's been approved by the US military to lubricate a wide array of weapon systems, as indicated on the 'military' page at http://www.mil-comm.com/. Their site layout may change and break the direct link, hence I've included a link to the top of their site as well. TW-25B may or may not be the sole approved lubricant for these systems, but at the very least it is an approved lubricant for each system.

Marvel Mystery Oil

MMO's composition is listed as "Mixture of mineral spirits, napthenic hydrocarbons, and chlorinated hydrocarbons". The chlorination probably means that it's using chlorinated parrafin, which can break down into hydrochloric acid and etch the metal it's supposed to protect.

Brake Cleaner

A lot of folks favor brake cleaner. It is typically only available in aerosol form nowadays, but I was able to obtain a gallon jug of it at NAPA Auto Parts. It's typically sold online for around $25/gallon.

Kano Kroil

Kroil is an excellent lubricant and penetrating oil. I personally use it on AK barrels which I'm pressing into trunions. However, it's definitely worth keeping in mind that Kroil's vapors are highly toxic and it should be used sparingly. Although it doesn't list carcinogenicity as a threat, it can cause chemical pneuomonia from over-inhalation. I would be primarily concerned with it if I were working in a small, unventilated area and managed to spill it. In quantities used for AK barrel installation, and only done occasionally, it's probably not a significant problem.

Motor Oil

There's some controversy about motor oil. Although not marketed for firearms, many of the core functions of motor oil are the same as the core functions for guns, and it's considerably cheaper. Primarily at issue is that motor oil is typically more viscous than dedicated gun oil, and is said to pick up crud more readily because it was designed for use within a fairly closed system (a car) and not a holster, where lint and such can be readily picked It's also worth noting that motor oil washes off of steel fairly readily under rainfall in informal testing, while dedicated anti-corrosives (CorrosionX was tested) can provide longer lasting protection.

3 in 1

This is a lightweight oil which is frequently used as a cutting oil for drill presses, lathes, mills, etc. Numerous folks have said it should not be used as a gun oil, but not why.

WD-40

WD-40 is like 3 in 1 in that it is frequently cited as a lubricant the uninformed may choose to use. I suspect that its main fault lies in that it quickly strips off of the gun.

Miltec-1

Miltec-1 is marketed as a 'metal treatment', which activates with temperature. It's a chlorinated alpha-olefin (halogenated hydrocarbon), which will more or less bake itself on as the gun is fired.

It is also recommended for the material used in AR-15 / M-16 A2 stocks, for the same reason. It produces a dark, lustrous finish which, when frequently applied, can approach the dark finish of the nylon A1 stocks.

This is a CLP formulation put out by Muscle Products Corporation (MPC). It employs halogenated hydrocarbons, although they claim the acids are neutralized by other chemicals in their mixture as soon as they're precipitated.

Break-Free has been described as 10wt oil, with particles of teflon suspended in it. The particles of teflon adhere to the metal. It is worth noting that over time the teflon will separate out, and it should be shaken or stirred before use. Otherwise, the teflon settles down at the bottom and you're only spraying oil on your firearm, no teflon. This probably means that CLP is not very good for use in a parts washer, as the teflon will settle to the bottom and stirring it will also bring the sediment from the bottom of the tank back into active circulation. Probably not a big problem if you're cleaning a LOT of weapons and don't mind frequently replacing your CLP, though.

Teflon fumes are particularly toxic, so if you choose to 'bake' a weapon with a teflon finish, it's advisable to do so in a well ventilated area.

Under extreme heat, teflon will clump up. However, it's unlikely for civilian guns to reach the requisite temperatures for this to happen with any regularity. This should be considered a non-issue during operation, but potentially an issue when attempting to 'bake' a firearm with teflon on it.

Military (D-5 formula) Break-Free CLP is 20% solvent by weight, while the civilian (E-formula) version is 12% solvent by weight.